While Statement

Executes a sequence of statements while a given condition is true.

Syntax

While condition
    [ statements ]
End [ While ]

Parts

condition
Necessary Boolean expression
statements
Optional one or more executable statements. They execute while condition is true.
Alternatively, two or more groups of statements. The first group starts with Begin, and executes the same as specified above. The subsequent groups start with When, and execute after the end of the loop. See When statements below for more information.
End
Completes the statement. You can also use End While.
You can change this part of the syntax. See @Option Directive for more information.

Instructions

Notice: End While is not the same as Exit While.

Use the construct While when you must execute one or more statements again and again. It is recommended when you cannot be sure how many times the statements must execute. Control depends on the Boolean condition after While. Other loop constructs are possibly more flexible or can give better performance. See the See also section below for more information.

Usual execution

If condition is true, then statements execute. After End, control moves back to While, where condition is calculated again. If condition stays true, then statements continue to execute. If it becomes false, then control moves to the statement after End.

While always calculates the condition before statements execute. If condition is initially false, then the statements do not execute.

Exit While

The statement Exit While can stop While. Exit While immediately moves control to the statement after End.

When statements

To find if While completed because condition became false, use When %Done.

To find if While was not executed because condition was initially false, use When %None.

See Begin…When Statements for more information.

Examples

Dim counter = 5
Dim factorial = 1

While counter > 0
    factorial *= counter
    Counter -= 1
End While

See also